Touch screens are common information entry equipments at present, which allow man machine interaction in a simple, convenient and natural way, and become a new type of multimedia interactive equipments. Capacitive touch screens have advantages such as sensitive touch response and support for multipoint touch. The Advanced-super Dimensional Switching technology (ADS) can improve the picture quality of TFT-LCDs and has advantages of high resolution, high transmissivity, low power dissipation, wide viewing angles, high opening ratio, low chromatic aberration, and no push mura, etc. In view of the above, ADS capacitive touch screens have become popular for medium and high end mobile phones in the world.
FIG. 1 is a simplified schematic diagram showing the structure of an ADS type TFT-LCD. With reference to FIG. 1, a prior art ADS type TFT-LCD comprises: an array substrate 8, a color filter substrate 9 and a liquid crystal layer 10 filled in between the array substrate 8 and the color filter substrate 9, wherein the array substrate 8 has strip common electrodes 81 formed on a side close to the liquid crystal layer 10, and the common electrodes 81 can form planar electric fields in the liquid crystal layer 10 which can control deflection of liquid crystal molecules in the liquid crystal layer 10 for liquid crystal display; the color filter substrate 9 has a layer of transparent conductive film 91 deposited on its back surface to mitigate influence of static electricity in external environment on display quality.
It can be seen that a layer of transparent conductive film function as a static electricity protective layer is deposited on the back surface of the color filter substrate during manufacturing process of prior art ADS TFT-LCD to mitigate influence of static electricity in external environment on the display quality. In addition, during the manufacturing process of a capacitive touch screen, a metal film and a transparent conductive film are deposited sequentially on a glass substrate. If a capacitive touch screen is made on an existing ADS product, the static electricity protective layer (e.g. ITO layer) of the ADS product will certainly form a large capacitance with the capacitive touch layer (e.g. ITO layer), thereby compromising sensitivity of touch response. However, omitting the static electricity protective layer for ADS will influence display quality of a LCD.